Telephone-exchange system.



G. DEAKIN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED AUG.16|1917. LQQSS, Patented Feb. 4, 1919.

4 SHEETSSHEETI MEE G. DEIMNl TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED AUG.16I917.

Patented Feb. 4, i919.

4 SHEETS-SHEET 2.

j Nui IN VER/WUR t /J o' 164%/ G; DEAKIN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED AUG.I6, ISI'I. lw@ @amm Een L wm.

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WTNESSEAS G. DEAKIN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED AUGJG, 1917.

lPafmued Fab. 4, 1919.

4 SHEETS-SHEET 4.

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GERALD DEAKIN, OF LONDON, ENGLAND, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented Feb. 4l, 1919.

Application led August 16, 1917. Serial No. 186,054.

To all whom t may concern:

Be it known that I, GERALD DEAKIN, a

a citizen of the United States, residing at London, England, have invented certain new and useful Improvements in Telephone-EX- change Systems, rof which the following is a full, clear, concise, and exactA description.

This invention relates to telephone eX- change systems employing machine switching of the type wherein a sensitive register is employed at the central oflice which is set by a sender manipulated by the calling party. Vhen the register is so set power is automatically applied to the selector to drive it in a continuous movement to a point detei-mined by the set register.

The object of the invention is to provide an improved automatic switching means for systems of this character.

Referring to the drawings in Figure 1 is shown diagrammatically, the physical structure of a selector switch. In Fig. 2 a connector switch is similarly shown. A section of the multi-coil electromagnet, operating the stops, which in turn limit the vertical movement of the shaft, is shown'in Fig. 3. Fig. 4 is a cross section of the air cylinder and piston, which operate the shaft. In Fig. 5 is shown ay subscribers line circuit with its central office connections includingythe circuit of the distrbuter vswitch and of the master switch. In Figs. 6 andv 7 are shown the selector and connector circuits respectively.

The selector switch indicated in Fig. 1 consists of a shaft 1, on which are mounted but insulated therefrom, three-wipers 31a, 31?) and 310. The shaft, in its normal position, is capable of vertical and rotary motion in the order given and in the direction of the arrows. The wipers, upon the proper movement of the shaft as above indicated, are arranged to engage any one of a number of sets of fixed terminals, 32a., 32o and 320, generally called switch bank contacts. In the preferred form of my invention, each group of bank contacts (three groups being required to meet the circuit conditions), are arranged in ten rows of ten each. Withsuch an arrangement, the shaft may be required to assume any one of ten different vertical positions and the corresponding. number of rotary positions. A reasonably air-tlght cylinder 2 contains a piston 3, the latter being attached rigidly to shaft 1, which shaft is arranged to slide through a hole in the top of cylinder 2 and through another in the center of disk L1. These holes act as bearings or guides to the shaft. Disk 4 is capable of rotary movement with the shaft by virtue of key la, which is attached to the shaft, but not of vertical movement. Passage 5 normally closed by valve7, leads to a source of compressed air. Outlet 6 normally opened by valve 7 acts as an exhaust outlet to air chamber 8. B is an electromagnet controlling valve 7 When energized it causes valve 7 to close the exhaust outlet .6 and open the inlet 5, allowing compressed air toenter chamber 8. Shaft 1 is held by a spring or otherwise (not shown so that Wipers tend to remain at the left o and below the switch banks. C is an electromagnet having ten concentric and adjacent windings, as shown in detail in Fig. 3. Each winding controls a stop, 'D1 to D10. These stops do not normally interfere with the vertical movement of shaft 1. l When, however, one of the mag net windings is energized, the corresponding stop is brought forward so as to engage the shaft when the latter is moved vertically. In Fig. l, stop D4 is shown in an operated position. The stops, for convenience in illustration, have been placed so as to engage the top of the shaft, the surface of the stops and the top'of the shaft being so shaped as to cause the shaft and wi ers to be turned toward the right, in the dlrection of the arrow, when the two come into forced contact. The

construction and operation of the air cham-V ber and piston is as follows: Upon energizing the valve controlling magnet B, air under pressure is allowed to enter chamber 8. Thls causes cylinder `3 to rise until the top of shaft l engages a stop, which, in Fig. 1, would be stop D4. The shaft on striking the stop, is turned toward the right with the result that the air compressed inchamber 9 through opening 10 and normally prevented from passing through opening 11 by the smooth side of cylinder 3 now passes through opening l1 and engages the piston vanes or blades 12, Fig. 4, which, being part of the piston 3, were brought opposite opening 11 by the turning of the shaft, the piston now turns under the pressure of the air. rllhc air traveling between the vanes and eX- hausting at 3a and 2a. As will be explained later on, release magnet Q, Fig. l. controlling armature Q1, is energized during rotation. Upon the selection of an idle trunk, this electromagnet is denergized, thereby, and allows armature Q1-to return to its normal position and projection Q2 to engage a slot 13 on the periphery of disk 4, which was opposite Q2 at the moment of release. When the movement of piston 3 is stopped the pressure in the air chambers 8 and 9 is increased to the maximum. Under this condition, valve 14 operates against the tension of adjustable spring 15. The operation of this valve opens contact 16. At this point in the operation of the switch, valve controlling magnet B is denergized, thereby allowing valve 7 to cut off the supply of compressed air and open the exhaust to air chambers 8 and 9. The switch is held in its operated position during a connection by armature Q1. To release the switch this armature is again attracted by electromagnet Q. The removal of the retaining finger Q2, from slot 13, allows the shaft to rotate back under the tension of the spring previously mentioned and then drop vertically toits normal position under the force of gravity or otherwise. Contact 17 is adapted to close whenever shaft 1 is moved out of its normalposition, arm 18 being rigidly fixed to the shaft.

The switch shown in Fig. 2 is similar to that shown in Fig. 1, with the one important difference that the rotar as well as the vertical motion of the shaft is controlled by a series of stops. Corresponding parts are similarly numbered. This switch in its vertical movement of the shaft operates exactly as described in the previous paragraph. Upon reaching the predetermined level, the shaft is given a turn to the right in the usual manner, which causes the wipers to engage dead bank contacts 18, or their equivalent, the sole object of which is to retain the shaft in its vertical position when valve controlling magnet B is denergized. The rotary movement of the switch 1s limited by stops F1 to F10, controlled by electromagnet E, having 10 windings El: to E10. The construction of these stops is similar to those at C. The energization of any one of the 10 magnet windings would elevate a` stop, which in turn would engage arm 19 attached to the periphery of disk 4a, and thus limit the movement of the shaft when the latter rotates. Contact 125 closes upon the initial rotary movement of the shaft.

Disk 4, Fig. 1, contains ten slots 13. Disk 4a in Fig. 2 contains eleven slots, 13. In each case the first tooth 13a, is beveled so as to permit sto Q2 or armature Q1 to be forced over this tooth into the first slot when the shaft is iven its initial rotary movement, by striking a stop D1 to D10. With stop Q2, Fig. 1, in the first slot 13 on the periphery of disk 4, the wipers 31a, 316 and 31o would be in contact lwith terminals in the first vertical row. of the switch banks 321:5,

iaeaeeo 326 and 320. With the stop in the next slot the wipers would be in contact with terminals in the neXt vertical row to the right and so on to the last vertical row. The arrangement of slots in the periphery of disk 4a, Fig. 2, are similar, the difference being that with stop vQ2 in the rst slot the wipers are in contact with the dead terminals 18 of the first row. The wipers do not come into actual contact with the switch banks proper until Q2 reaches the-second slot.

The function of the selector or trunking switch, Fig. 1, is to select one of a number of groups of trunks corresponding to the digit called and then to automatically select the first idle trunk in that group.

The switch shown in Fig. 2 illustrates what is now well known as a connector; the function of this switch is to complete the last stage of any connection and it operates in response to the last two digits. In the particular form disclosed in the drawings the extent of the vertical motion is controlled by the next to the last digit and the rotary motion by the last digit.

The function of the third switch, herein called a distributer switch, is, as before stated, to hunt out the calling line and connect it to the selector associated with the distributer, there being one selector for each distributer. v This latter switch, in the preferred form of my invention, has access to a bank of line contacts arranged in one con* tinnous row instead of in horizontal and vertical rows, which is the arrangement lof the banks for selector and connector switches, Figs. 1 and 2. vB arranging the banks in one row the distri uter is required to rotate or move in one direction only when selecting a line, and for the purpose of explanation, the distributer switch may be assumed to'be of a type similar to the selectorswitch, Fig. 1, with those features pertaining to the vertical movement of the shaft omitted. Each distributer of this type would consist of a shaft and wipers, a cylinder adapted to rotate within an air chamber, a means of holding the shaft in its operated position, such as disk 4, and release coil Q of Fig. 1, a valve controlling magnet such as B, Fig. 1, adapted when operated to allow air to enter the air chamber and rotate the cylinder, and a relief valve such as 14, adapted to operate after the manner previously described when the movement of the cylinderl is stopped, thereby causing the pressure in the air chamber to be increased to the maximum.

At G in Fig. 5 is shown a simple form of a subscribers telephone circuit, consisting of transmitter G3, a receiver G4, a switchhook and contact G5,v calling device contacts G6, adapted when operated to make and break the line circuit, a condenser G2 and' a ringer G1. LP and LN are line conductors connecting the subscriber-s station at G with the central oli-ice at H. The line conductors terminate in two groups of switch or bank contacts. The first group of contacts H1, H2, etc., are'. distributer bank contacts, accessible to the distributer switches. The second group HHl, etc., are connector bank contacts, accessible to the connector switch. Associated with each subscribers line is a cut-ofi' relay H3, having two contact springs H4 and H5, the former'adapted to remove, when relay H3 is energized, a ground from line conductor LP, and the latter a common lead to the master switch circuit J from conductor LN. With each group of subscribers lines there is associated a master switch the circuit of which is shown at J. This circuit controls the distributer switches through master wipers J6 and J7 and master bank contacts J8 and J9, there being one set of bank contacts for each distributer switch. In a typical arrangement there would be approximately ten or fifteen distributer.'

switches for each one hundred subscriber lines, the whole being served by one master switch circuit. Relay J2 is a quick acting relay in starting, but designed to be sluggish in releasing. This re ay controls the motormagnet J 1, whose armature J4 engages the ratchet wheel J 10 to which is attached, but

insulated therefrom, wiper arms J6 and J7. Each energization of the master magnet J 1 causes the. master wipers to step ahead one set of contacts. Relay J3 is adapted to cause the master mechanism to continue to rotate should adjacent contacts be found busy.

The circuit of a distributer switch is shown at K. B is the electromagnet controlling the air inlet valve which in turn controls the rotation of the shaft. Q is the release magnet which maintains the switch in an operated condition during the connection and releases it when the calllng subscriber hangs up. Relay K through a contact on relay O is connected to the negative wiper WN, which wiper is adapted to en gage bank contacts such as LNl. O 1s a slow release relay. K and are qulck acting relays. Contact 23B is closed by the operation of a relief air valve, such as 14, Fig. 1. Contact 126 closes Whenever the wiper shaft is moved out of its normal position. With each distributer switch 1s associated a selector switch. Conductors LP2, LN2 and L2 of Fig. 5 also appear in Fig. 6.

The circuit of the selector switch, Fig. 1, i's shown in Fig. 6. C represents the multicoil electromagnet controlling the shaft stops D1 to D10, shown in Fig.- 12 B is the electromagnet controlling the alr lnlet valve and Q the release electromagnet. M and C are relavs of the sluggish release type. Contacts 16y and 17 are controlled by the air relief valve and shaft respectively. W1, WPl and WNl, are wipers adapted to engage bank contacts L3, LP3 and LN3 respectively leadingto' the next switch. The impulse recording apparatus may be called the register, and operates in response to the impulses sent over the line conductors by the calling subscriber. Electromagnet R, which is in the line circuit, responds to each interruption of the line circuit by the calling device at the calling station and correspondingly rotates ratchet wheel 35 through its armature 40. To ratchet wheel 35 is fastened shaft 36. Attached to shaft 36, but insulated therefrom, is a wiper 37, adapted to engage bank contacts T1 to T10 when the shaft is rotated. An insulating stop or bushing 38 is also attached to the shaft. Slow acting relay S, in addition to opening contact 33 when energized, also attracts the armature of pawl 34 which holds the ratchet wheel in its operated position between impulses when R is momentarily denergized. The insulating bushing 38 is arranged to allow contact 39 to close upon the first energization of electromagnet R. The adjust- Ament between 40 and 41 is such that the contact does not break until just before the full movement of the armature. This contact is also closed again immediately after the electromagnet is denergized and before the armature reaches its normal position. The object. of this adjustment is to permit the closing of the local circuit through relay S and thereby cause the holding pawl of 34 to .engage the ratchet wheel before the latter is removed from the control of the armature 40. It should be stated that shaft 36 is provided with a spring tending to cause it to resume its normal position.

Any number of switches arranged as indicated in Fig. 6 may be used in establishing a connection. All connections, however. must be completed by a connector, the circuit of which is shown in 7. Conductors L3, LP3, LN3, Fig. 6, may be connected with the corresponding conductors in Fig. 7.

In Fig. 7, the register operates inexactly the same manner as the register shown in Fig. 6. In the connector circuit. however. a second set of bank contacts T11 to T20 is provided. These contacts are connected to the multi-coil magnet E, which limits the rotary movement of the shaft. The multicoil magnet C controlling the vertical movement of the shaft, is connected to contacts T1 to T10. B, Q. 0' and M perform the same functions as B, Q, C and M in Fig. 6. U is a balanced bridged line relay land supplies current to the calling subscribers line for the transmission of speech. 89, 90 and 91 are condensers of suitable capacity. Relay X in series with interrupter 118 supplies ringing current to the called subscribers line relay. Relay Z applies a busy tone to the calling subscribers line in case the called line is busy. Relay N operand LNl, Fig. at HHl. F or the purpose of this description the same subscribers line circuit, H, Fig. 5, may be treated as both the calling and called line.

` Ve may now proceed with the operation of the system, considering first the changes '66 f Windin -of B', 26 to earth again at 25,

'of the line LP, H4 to earth 25. operates, closes contact between 44a and 44?) which take place when a subscriber removes his telephone from the hook switch to originate a call.

The closing of the line circuit at switchhook G5, Fig. 5; establishes a circuit through the starting relay J2 of the associated master switch crcult'Jthe circuit extending from earth 25, through battery 26, contact 43, winding of J2, contact H5, one side of line LN, calling device G6, switchhook G5, receiver G4, transmitter G3, the other side Relay J2 and energizes the motor magnet J 1, causing it to attract its armature J4 with a result that ratchet wheel J 10 is turned one notch, causing wipers J7 and J6 to engage the next set of bank contacts. The moment contact 44 a-b is closed and before armature J4 has broken contact 45, a ground is momentarily placed upon wiper J6 connected through bank contact J9 to the air inlet valve controlling magnet B' of the distributer whose bank contacts J8 and J9 happen to be engaged lby wipers J7 and J6 at the moment the call was originated. The closing of this momentary circuit from earth 25, through 44 a and b, 46 a and I), 45, J6, J9,

Relay J2 as before causes to operate.

stated is sluggish in releasing so that after` being energized and opening contact 43, it remains energized for a short time, the length of which is determined by the speed with which the distributers can be operated. It is intended that the interval of time during which contact 43 is open shall be sulicient to permit a distributer to be started by the operation of a magnet B' and to select the calling line, at which timethe cut-ofi' relay H3 of that line is energized and connection between the calling line and relay J2 broken at contact H5. By adjusting relay J2, in this manner, the wipers J6 and J7 will be allowed to engage the banks of the next distributer, but will not start that distributer on a hunt for a calling line, since the ground necessary to start the distributer and normally on Wiper J6, is removed at 45. Under the arrangement just described, when relay J2 again resumes its normal position and closes contact.43,it is not again energized by the same calling line.

Therefore, the master wiper` remains in the next position in readiness for the vnext call provided the next switch is not busy. Should the next distributer be engaged when wipers J6 and J7 are moved into contact with its banks, wiper J7 will engage a grounded bank contact, the ground being supplied by the busy distributer K, Fig. 5, as will be explained later, from 25 at K, through shaft contact 126, 49, 48 to bank contact J8. A circuit is now closed; through relay J3 from wiper J7, 47, winding of J 3, 26, 25. itelay J3 when energized opens contacts 46 a-b and 47. The .former releases motor magnet J l and allows pawls associated with armature J4 to engage the next notch on ratchet wheel J 10. The local circuit through J3 is opened at 47 so that this relay tends to vibrate, and at each vibration the circuit of the motor magnet is opened and closed, thereby causing the ratchet wheel to step ahead one notch. rlhis vibration continues until a non-grounded bank contact J8 is found, at which time the circuit through relay J3 is opened. Even with relay J2 deenergized wipers J6 and J7 cannot remain on busy contacts. Each time relay J3 is energized as just explained, motor J 1 is operated, a circuit being established from 25 through 44a, 440, 46c, 46a, winding of J 1, 26 to 25.

We may now consider the operation of the distributer switch shown at K, Fig. 5, rilhe energization of B', as explained in the preceding paragraph, opens the air inlet valve which causes the switch wipers to rotate in their hunt for the calling subscribers line, the wipers WP, WN and W engage a series of fixed bank contacts such as LPl, LNl and P,respectively. Upon the first movement of the shaft, contact 126 is closed and a circuit established through the release magnet Q', which permits the rotation of the shaft, a circuit being established from 25 throu h 126, 49, 50, 55, winding of Q', 26 to 25. 'lille wipers in passing over idle lines nd a ground on bank contacts LPl through contact H4 of the cut-olf relays H3, and battery on bank contacts LNl, through the common master switch relay J2 and the cut-off contacts H5 of the cut-ofi'A relays. Normally the circuit of wiper WP is opened at 51. Wiper WN, however, is connected to battery through relay K and contacts 53 and V54. Under the conditions just mentioned,

this relay does not operate. Furthermore,

bank contact P of each non-busy line, is

connected to battery through the winding of its associated cut-off relay. This contact, however, on engaged lines is grounded, the ground extending from the first selector, as will be described later on, over conductor L2, to wiper 1V. Relay l attached to circuit of wiper W is connected to battery through the closing of 'contact between 56 have to pass over two classes of lines', en-

gaged lines and non-engaged lines. On passing over non-engaged lines neither relays K or K are energized. In passing over engaged lines, both relays K and K are energized. The current through relay K starts at the ground supplied by the distant connector to the positive side of the engaged line indicated at H by conductor LPl, and thence through the subscribers telephone set ba'ckover the other side of the engaged line indicated by conductor LN, at H, thence to the switch banks, at which point it divides, part extending` to the other side of the connector circuit associated with the v engaged line, and part through wiper WN, contact springs 53 and 54, winding of K to battery 26 and earth 25. The circuit through relay K originates with the ground `found upon the engaged line bank contact P through wiper W, winding of K, 58, 56, 26 to 25. AThe energization of relay K opens the circuit through the release coil Q, at the same time the circuit is closed by the energization of K. In this way the switch is allowed to rotate by engaged lines. When the line of the calling subscriber is found relay K is energized, but not relay K, there being no ground on bank contact P to energize the latter relay. Relay K is energized by a current which may be traced from ground 25 at the cut-off relay H3, through H4, LPysubscribers set at G, back over conductor LN to LNl, at which point the current divides part passing through the master switch relay J 2 and contact H5 and ythe remainder through wiper WN, 53, 54, winding of K,'26 to 25. The energization of relay K in this case opens the release coil Q circuit at 55, and allows the stop controlled by this coil toengage a slot on the wiper shaft and retain the wipers in contact with the switch banks LPl, LNl and P of the calling subscribers line. The stopping of the rotating the'air relief valve previously referred to, to operate and close contact 23?). Relay Q is now energized, a circuit being established from 25, Vthrough 126, 49, 50, 235, winding of O, W, P, winding of H3, 26 to 25. The operation of relay O closes the line circuit from WP and WN to LP2 and LN2 respectively to the associated selectorshown in Fig. 6. The opening of contact between 49 and 50 denergizes B. The closing of contact between 48 and 49 places a ground upon the wire leading to `the master switch bank contact J 8. and makes this distributer busy at the master switch. The ground which retains sluggish relay O and cut-olf relay H3 in their energized positions, is

"supplied by the associated selector over conductor L2 as Will 'be described later.

mechanism causes.

The function of contact 235 is to give relays O and H3 their initial energizatlon. This contact resumes its normal position when valve magnet B. is denergized.

The distributer in its final position extends the calling line through to the selector. Fig. 6, placing electromagnet R, Fig. 6, of the register forming part of the selector, in series with the calling line, a circuit being established from earth 25, Fig. 6, through one winding of R, 463, 64, conductor LP2, to distributer K, Fig. 5, through 51, WP, LPI, LP, through the substation G, back over the opposite side of the line LN, LNl, WN, 53,- 52, conductor LN2, to the selector', Fig. 6, 70, 71, the other winding of R, 26 to 25. The closing of this circuit energizes TR, which attracts its armature 40, opening contact between 40 and 41 and causing ratchet wheel 35 to step ahead one notch and in so doing turn shaft 36 a suhcient distance to close contact 39` but not sufficient to close contact between wiper 37 and bank contact T1. The. register mechanism is so designed that a turn of the ratchet wheel of two notches is required to close this circuit. Contact between 40 and 42 is also made. The result is that a ground is placed on the holding wire L2, vfrom 25 through 39, 40, 42 to L2, thence over this conductor to the distributer, Fig. 5, through Winding of relay O, Fig. 5, 57, 56, 26 to 25. This ground also energizes the cut-od relay. associated with the calling line as it forms a closed circuit from L2, through W, P, Winding of H3 to battery 26 and earth 25. The energization of relay 0 maintains the distributer in its operated position.

1We have now arrived at thepoint Where the calling subscriber may proceed to send 1n impulses by manipulating the calling devlce, G6, Fig. 5, provided for the purpose. rIhese impulses thus made are ofshort but equal duration. Relay S of the register in Fig. 6 is of a sluggish release type, such that contact-33 opened on the first impulse when'R is-momentarily denergized, is not closed again until the impulses cease. At

each impulse or interruption of the line circuit at G6, magnet R is denergized and then renergized with a result that ratchet wheel 35 is caused to step ahead one notch for each impulse. Similarly, wiper 37 is caused to step ahead one bank contact for each notch engaged by the pawl of arma-` 26 to 25. At the end of a series of impulses, relay S is denergized, due to the prolonged opening of its circuit between 40 and 41 and closes contact 33. The ratchet wheel 35 is maintained in its operated position by armature 40, magnet R remaining energized between each series of impulses. Therefore, wiper 37 remains in contact with the particular bank contact selected in response to the digit called. For example, in case the digit 8 were called, the eight impulses received by R would step wiper 37 into contact with T8. The result is that a circuit is closed from ground through wiper 37, T8, through winding C8 of the electro-magnet C, 33, B, 67, 66, 26 to 25, energizing both C8 and B. Stop D8, Fig. 1, thus caused to operate, engages the switch shaft which moves vertically when the air inlet valve controlled by B is opened. The shaft upon striking the stop is turned to the right, giving the shaft a rotary movement, as previously explained. This preliminary rotary movement of the shaft causes wipers 71. WPl and WNl to engage bank contacts L3, LP3 and LN3 respectively, of the first trunk in the group corresponding to the level or row to which Wipers have been raised. Should this first trunk be busy, a ground will be found upon bank contact L3, which ground will be transmitted by wiper W1 through 61, 60, winding of Q, 26 to 25. Q, is now energized, which removes the holding stop from the disk on the switch shaft and allows the latter to rotate under force of the air in a manner which has alreadv been described. Bank contacts L3 of non-busy trunks are connected to battery instead of to ground. Therefore, when a non-busy trunk is picked up by the rotating wipers, the circuit through Q is immediately opened. The denergization of this coil allows the holding' stop Q2 to return to its' normal position and engage a slot 13 in disk '4, Fig. 1, and thus maintain the wipers in con tact with the terminals of the idle trunk. The stopping of the shaft causes anincrease in air pressure which operates the valve opening contact 16, Fig. 6. The opening of this contact removes a short circuit from the winding of relay M, thereby causing this relay to operate. Relay Mv is now placed in series with relay OQ which latter relay was energized when contacts 39 and 40-42 were iirst closed. Both relays remain energized until the calling subscriber hangs up. The operation of relay M removes R from connection with the calling line and connects the latter straight through to wipers WPI and WNl, the transfer taking place at contacts 64, 63, 65 and at 70, 71 and 69. The opening of contact between 60 and 61 removes the winding of Q from connection with the wiper W1. The closing of contact between 61 and 62 connects con- L3 allows relays O and M to release.

ductor L2 to wiper Wl. The ground sustaining the connection is now supplied from the next switch over conductor L3, in the same manner that it was supplied to conductor L2 before relay M was energized. Contact 17 is controlled by the switch shaft and closes whenever the shaft is `mdved out of its normal position. The release circuit is opened at 73, during the connection. Air control contact 16 after opening again closes when air pressure is reduced to normal, which takes place when contact is opened between 66 and 67. The opening of this contact releases B and C. The opening of contact between 66 and 68 removes the short circuit from the winding of M when contact 16 is again closed. The opening of the circuit through R--allows armature 40 to resume its normal position and in so doing allows ratchet wheel 35 and wiper 37 to return to their normal positions, at which time Contact 9 is again opened. lVe now have a clean pair of wires from the calling subscriber-s station through a distributer, a first selector to the next switch. In case the connection is to be again trunked, a second, third and, if necessary, fourth selector may be used. The circuit of these additional trunking switches is the same as that of the `rst selector and for this reason need not be described. As the connection proceeds the last switch added to the chain always holds the preceding switches busy.

Should the calling subscriber hang up after operating the firstselector, he will open the line circuit and denergize R of the register of the .next switch. The deenergization of this, magnet will remove ground fromconductor L3, it being placed on that conductor, as previously described, by the closing of a contact such as 39, Fig. 6. The removal of ground from conductor The closing of contact 73 energizes the holding coil Q, which allows the switch to return to its normal position, the circuit being again opened at 17 when the shaft reaches this position. The distributer is released at the same time by the denergization of relay 0, Fig. 5, the release circuit being established through release coil Q' from 25 through 126, 49, 50, 55, winding of Q', 26 to 25.` When this switch reaches its normal position, contact 126 is again opened. The removal of the ground from L2 also allows subscriber-s cut-off relay H3 to resume its normal position.

Should the calling. subscriber hang up without operating the first selector, register relay S is released by the opening of its circuit at 72. If the circuit were not open at this point it will be seen that a circuit would exist through relay S from 39, through 40. 41, 72, winding of S. 67, 66` 26 to 25. Holding coil Q is always energized on a disconnection, Whether or not impulses have been sent in, owing to the fact thai-contacts 39 and 40-42 are closed as soon as the selector is picked up by the calling line. Therefore, when relay O is released by the opening of contact between 40 and 42, the circuit through release coil Q is closed at 73 through 40, 42 and 39 to ground.

The last stage of any call is always'completed by a connector, thegeneral physical arrangement of which is shown in Fig. 2 and its circuit in Fig. 7. As soon as the Awipers of the preceding selector, Fig. 6,

engage the terminals of the trunk leading to the connector, Fig. 7, electromagnet R- of the register of the connector is energized, a circuit being closed from ground 25, through one Winding of R, 77, 78, conductor LP3 to Wiper WP1 of the selector, Fig. 6, 65, 64, conductor LP2 Lto the distributer (Fig. 5), 51, wiper WP, one side of the calling subscribers line LP, through tele-y phone set at G, back over the other side of the subscribers line LN, Wiper WN, 53, 52, conductor LN2'to the selector (Fig. 6), 70, 69, Wiper WN1, to conductor LN3, to the connector (Fig. 7), 84, 85, 106, the other Winding of R, 26 to 25. The 'energization of R places the ground on conductor -L3` through 39, 40 and 42. The grounding of this conductor holds all preceding switches in their operated position by the energization of relays O, O', Figs. 5 and 6 respectively. Relay' O of the connector is'also energized, a circuit being established from grounded conductor L3 through the Winding of O, 82, 80, 26 to 25. The energization of relay 0 opens contact 86 and prevents the-energization ofrelease coil Q, which would otherwise take place, since the armature of O is grounded throughlthe conductor terminating at contact 17.

The iirst series of impulses given the connector by the calling subscriber cause R to step ratchet Wheel 35 and Wiperr37 around 'to the Iproper bank contact T1 to T10. When the impulses cease, relay S resumes its normal positionas previously described,

closing a circuit through the proper Winding of thev electromagnet C, the circuit being closed from grounded Wiper 37, through the proper bank contac't T1 to T10, through the proper Winding of C, 21, 20, 110, Winding" of B, 109, 108, 26 to 25. This results in the energization of the proper coil on C and the air inlet valve cont-rolling magnet B. The opening of the air inlet valve causes 'the shaft to move vertically `until it engages the stop `operated by C, at which time the shaft, as previously described, is given a preliminary turn to* the right, causing the Wipers to engage a dead bank contac't 18, see Fig. 2. The shaft is held .in this position by the finger or stop Q2 on armature Q1, which was forced over the beveled tooth 13a, into the first slot 13 of disk4a, Fig. 2. Referring again 'to Fig. 7

the stopping of the shaft 'causes contacts 23 and 23a, controlled by the air relief valve, to close. The contact closed by 23 operates relay Y. The operation of this relay does a number of things. 1t opens the circuit through electromagnet -R at 106, relay S, valve controlling magnet B and stop magnet C at 109. The result is vthat these -magnets release, allowing lratchet Wheel 35 and Wipers 37 and 37a to return to their normal position. Relay Y is made sluggish in resuming its normal position so that ample time may be given for the release of the comple'te register. The closing of con't-act between 121 and 108 energizes lrelay AY; the circuit may be traced from 25, through 26, 108, 121, Winding of AY, 17 to 25, contact 17 having been closed when the shaft Was moved out of -its normal position. Relay AY now locks up through contact 120, a circuit beingl established from 25 through/17, Winding of AY, 120, 123, 95, 81, 80, 26 'to 25. Armature 20 breaks lContact with 21 and makes contact with 22. The switch is noW in a position to receive the second and last series of impulses, originated when the last digit of the Wanted number is called. These impulses operate R and S in 'the usualy manner. When the impulses cease, relay S again closes contact 110. A circuit is now established `from grounded Wiper 37a, through the proper bank contact T11 to T20, through 'the proper Winding of rotary stop controlling magnet E, through one Winding of Q, 22, 20, 110, Winding of B, 109, 108, 26 lto 25. The result is that. the

proper coil of E, Q and B are energized. The energization of B controlling the air inlet valve, Acauses the switch shaft to roltate. The energization of Q"\removes the holding stop from disk 4a (Flg. 2) and `permits this disk to rotate. The energizavlwhich will close a circuit through Wiper 72, 75, 74, 101, 102, vwinding of Z, 23a, 26 to 25. Z now operates and locks up through contact 94, a circuit being established from the grounded bank contact P through 75, 74', 101, 102, Winding of Z, 94. 111, 26 to 25. The closing of Contact 92 places a. busy tone on one side of the calling line LPS,

through condenser 90. Lead 90a leads to a suit-able busy tone 'transformer or other device. The opening of contact 93 prevents the energization of relay N. The Switch now remains in this position until the calling subscriber hangs up, there being no connection between the talking circuit of the called line branch of the connector and the calling line branch. When relay Y resumes its normal position, electromagnet R is again placed in the calling line circuit and holds the connection busy through the contacts 40 and 42. During the interval in which the circuit of R is opened, the ground removed from conductor L3 by the release of the ratchet wheel 35, thereby opening contact 39, is supplied by closing of contact 124 on relay Y. When the calling subscriber hangs up and opens 'the line circuit, electromagnet R is denergized. This removes the ground'from conductor L3 by opening the contact between 40 and42 and allows relays O Fig. 7, O Fig. 6`and O Fig. 5 to release and in turn close the release circuits of the connector, selector and dstributer, thereby causing 'these switches to resume their normal positions. In Fig. 7 this is accomplished by the closing of contact 86. A circuit is thus established from 25 through the onormal contact 17, 86, one winding of Q, 26 to 25. The energization of the release magnet Q removes the holding machanism and allows the switch shaft to return to its normal position, after which-.the oi-normahcontact 17 is again opened. It also releases relay Z by opening its locking circuit at 111. The ground found upon bank contact P of the engaged subscribers line may be supplied in one of two ways. In case the engaged line originated the call, the ground would be supplied over wiper W of the associated distributer as already described. In case the engaged line answers the call, the ground would be supplied by wiper W2 of the involved connector, as will be described later on.

Should the wanted subscribers line be unengaged, bank contact P of the wanted subscribers line will be found connected to battery through a cut-ofi relay, such as shown at H, Fig. 5. Therefore, relay Z will not operate when contact 23a is closed. Contact 93 remaining closed establishes a circuit through relay N from ground 25 at N, through winding of N, `93, 125, 107, 108, 26 to 25. Relay N operates and locks up, a circuit being established from 25 through N, 98, 96, 111, 26 to 25. Contact 125 was closed when the shaft was given the first rotary movement as previously explained. The closing of contact between 99 and 101 places a round on the free end of one winding ofine relay AN, the other end of which is connected t0 one side of the wanted line branch of the connector. The closing of contact between 96 and 97places battery on free end ofthe other winding of -line relay AN, the other end of which is connected to the opposite side of the called line branch of the connector. The closing of Contact between 100 and 101'places a groundf upon wiper W2 through closed contact 74 and 75, with the result that the cut-ott' relay of the wanted sufbscribers line is energized and the called line freed from all battery and ground connections through the opening of the cut-oil' relay contact. ground upon wiper W2 also makes the connection busy to all other connectors. The opening of contact between 95 and 123 releases relay AY. The closing of contact between 95 and 122 establishes a circuit through ringing relay X and the grounded interrupter 118, from ground 25 through interrupter 118, winding of X, 122, 95, 81, 80, 26 to 25. Relay X is thus caused to operate intermittently the interrupter 118 being adapted to-open and close the circuit. At each energization of relay X, contact is broken between 112 and 113 and between 116 and 117 and made between 113 and 114 and between 115 and 116. Ringing current is thus supplied from generator 119 to wipers WP2 and 12V-N2, thence over line conductors LPl and LNl to the called subscri-bers station such as shown at G, Fig. 5. At this point the ringin current passes through condenser G2 an ringer Gland operates the ringer. rlhe connector circuit remains in this condition until the called subscriber answers, lat which time the calling line circuit is closed by switch hook G5, Fig. 5. A circuit is now established for a How of direct current through the called subscribers telephone set. Therefore, during the next denergization of relay X, current flows through line relay AN, a circuit being established from ground 25 on relay N, through 100,- 101, 99, one winding of AN, 112, 113, WP2, bank contact LP1, line conductor LP through the telephone set at G, back over line conductor LN to bank contact LN1, thence through wiper WN2, 116,'

117 the other winding of relay AN, 97, 96, 111, 26 to 25. Relay AN is thus energized and closes contact lbetween 105, 103 and 104. rThe closing of contact 103 and 105 energizes relay M, which remains energized until the connection is released by the calling subscriber, it being placed in series with relay O by the open1ng-of contact between 80 and 82, which contact normally shortcircuits its locking winding. Electromagnet R is removed from connection with the calling subscribers line by the opening of contact between 84 and 85 and 77 and 78. The talking circuits of the called and calling line The placing of ice iat

etti

neeaeeo branches of the connector are connected through the closing of contact between 78 and 7 9 and between 83 and 84. rl`he closing, of these contacts places line relay U in series with the calling subscribers line. This relay is thus energized and in so doing closes contact 87, thereby grounding conductor L3 and holding the connection busy. The opening of contact between 74 and` 75 and the closing or Contact between 75 and 76 removes the control 'of the ground or wiper W2 from relay N to relay 1. The closing of contact between. 105 and 104C on relay AN short-circuits resistance 88 during conversa-- tion. When the called subscriber hangs up, relay AN is denergized and thereby removes this short circuit from the resistance, which is thus placed in series with the calling' line. Lhe object of this resistance is to aiiord supervision to private exchanges and other special switchboards which may be associatedwithv the calling subscribers line. The denergization of relay AN, however, does not release the connection. During conversation rela AN supplies current to the transmitter ciY the wanted subscribers line and relay U to the transmitter of the call ing subscribers line, the high frequency voice current being transmitted from one line to the other through condensers 89 and 91. At the end of conversation the calling subscriber hangs up, openin the line circuit and denergizing relay The ground is thus removed from conductor 13 by the opening of contact 87. Holding relays of the connector, 0 of thel selector (Fig. 6) and 0 of the distributor (Fig. 5) are now denergized, with the result that all switches are released and return to their normal position,

W'hat is claimed is:

l. ln a switch, the combination with a bank of terminals, a shaft having a brush, means for imparting a `primary and secondary movement to said shaft to select hrst a group and 'then a terminal therein, of sets of mechanical stops for limiting the primary and secondary movements of said shaft, electromagnetic means for selectively positioning said stops, and a sender for controlling said means.

2. lln a switch, the combination with a bank ot terminals, ashafthaving a brush, means `for driving 4the same in one direction to selectthe group and in another to select a terminal therein, a set of mechanlcal stops for limiting the group choosing movement of the shaft, electromagnetlc means lnclud. ing a sender for selectively positioning said stops, means 'for thereupon automatlcally actuating said driving means to cause said shaft to engage the posltloned stop, said stop being constructed and arranged to deect said shaft onto the rst terminal 1n the selected group, and means for arresting said brush upon one oit the terminals of. the

group,

3. n a switch, the combination with a bank of terminals, a shaft having: a brush, means for drivino the same in one direction to select'the group and in another to select a terminal therein, a set of mechanical stops for limiting,- the group choosing movement 'of the shait, electromagnetic means including a sender for selectively positioning said stops, means `tor thereupon automatically actuating said driving means to cause said shaft stop being constructed and arranged to de fleet said shaft onto the rst terminal in the selected group, and means for continuing the movement of the shaft and for arresting said brush upon one oi? the terminals of the group. A

i 4f. lin a switch, the combination with a bank of terminals, a shaft having a brush arranged to select rst a group and then a terminal therein by movements at an angle to each other, and means for driving said brush in a continuous movement to select irst the group and then a terminal therein.

-5. in a switch, an air chamber, a piston therein, means for admitting air into said chamber to drive said piston, means for stoppingy said piston, and a circuit changing vdevice constructed and arranged to remain inoperative on the operating air pressure but to become operated on the increased air pressure as the piston is stopped.

6. lin a switch, the combination with a bank of terminals, a shaft having a brush arranged to Select iirst a group and then a terminal therein by movements at an angle to each other, a chamber, a piston therein connected to said shaft, and means for operating said piston to drive said brush in both its movements.

7. ln a switch, the combination with a bank of terminals, a shaft having a brush arranged to select rst a group and then a terminal therein by movements at an angle to each other, an air chamber, a piston therein connected to said shaft, and means for ad- `mittingp compressed air to said chamber to drive said piston to actuate said shaft in both its movements.

8. lin a switch, the combination with a bank of terminals, a shaft carrying a brush, a chamber, a member fitted in said chamber 'and connected to said shaft responsive to i Huid pressure for imparting a rectilinear vmovement to said brush to select a group, said member being provided with vanos also responsive to fluid pressure 'or imparting to said brush a curvilinear movement to select a terminal therein.

9. ln a switch, the combination with a bank of trunk terminals, a shaft having a to engage the positioned stop, saidl liti Miti) brush arranged to select first a trunk 'group and then an idle trunk herein by movements at an angle to each other, an air chamber, a"

-cally actuating said driving means to cause said shaft to engage the positioned stop, said stop being constructed and arranged to deflect said shaft onto the irst, terminal of the group whereupon the compressed air rotates the brush over the trunk group, means for stopping the brush on. an idle trunk, and a circuit changing device operated by the increase in air pressure within said air chamber when the piston is stopped. 10. In a telephone exchange system, the

combination with telephone'lines, a sender,

an electrically operated registering device, a circuit including said sender and said device whereby the saine may be set, and a pneumatic switch thereupon automatically operated to interconnect said lines according to the set condition of said device.

11. ln a telephone exchange system, the combination with telephone lines, a sender, a regi-ster, a circuit includingV said sender and register whereby the same may be set, and a switch having a bank of terminals and a shaft carrying a brush adapted choose first a group under control of said register and then a terminal therein by a continuous movement in two directions.

12. ln a telephone exchange system, the combination with telephone lines, a sender, a register, a circuit including said sender and register whereby the same may beset, a switch having a bank of terminals and a shaft carrying a brush adapted to choose first a group under control of said register and then a terminal therein by movements at an angle to each other, and means for driving said brush in a continuous movement to said terminal.

13. ln a telephone exchange system, the combination with telephone lines, a sender, a register, a circuit including said sender and register whereby the same may be set and a switch having a bank of terminals and a shaft carrying a brush adapted to choose rst a group and then a terminal therein by movements at an angle to each other under control of said register, and means for'v driving said brush ina continuons movement to the desired terminal.

le. ln a telephone exchange system, the combination with telephone lines, a sender, a register, a circuit including said sender and register whereby the saine may be set, a switch including a bank of terminals, and a shaft having a brush adapted to choose 1,ees,eeo

first a group and then a terminal therein by movementsat right angles to each other under control of said register, said switch including v'a piston connected to said shaft and adapted to drive said brush in both its movements.

l5. ln a telephone exchange system, the combination with subscribers lines, a switch comprising a number of rows of terminals and a'set of wipers, mechanical stops, subscriber controlled' means for selectively actuating said stops, and a source of power for driving said wiper into engagement with vthe set stop, said stop and wiper being so constructed and arranged that the wiper is thereby given a movement of translation to carry the same along the selected row.

16. In a telephone exchange system, the combination with subscribers lines, a power driven switch having rows of terminals, trunks terminatingtherein, a subscriber controlled means for selectively advancing said wiper into operative relation to the desired group and for imparting to said wiper a movement of translation over the group without stopping the brush, and means for stopping the same on the first idle trunk.

17. In a switch, the combination with a bank of terminals, a shaft carrying a brush, a chamber, a member therein connected to the shaft, a port for the admission of fluid pressure into said chamber for driving-said member in a primary direction, a secondary port closed throughout the movement in the primary direction, and means operated at the termination of the primary movement for automatically opening the said secondary port, said member being provided with vanes responsive to the admission of fluid pressure through said secondary port to impart a secondary movement to said brush.

18. ln a switch, the combination with a bankof terminals, a shaft carrying a brush` for selecting rst a group and then a terminal therein, a chamber, a member therein connected to said shaft a primary port for the admission oit duid pressure into said chamber for driving said member in a primary direction, a set of stops for limiting the primary movement of the shaft, electromagnetic means including a sender for selectively positioning sazid stops, means for opening the primary ort upon the setting of the stop, said secon ary port being closed during the primary inovement'by a part' of said member, said stop being constructed and arranged to deect the brush 'onto the iirst terminal of the selected` grou whereby said member opens said secon ary port venes being provided on the member responsive to the admission of duid pressure through said secondary port to impart a secondary movement to said brush to select a snm. in the selected group, f

19. -lln a telephone system, an automatic switch including an element movable in two intersecting planes, means for moving said lelement by `a single continuous motion in both directions, step-by-step means for controlling the extent of operation of said movable element and circuits for controlling said operation.

:20. In a telephone system, an automatic switch including a movable element, means for moving said element by a single continuous motion in two directions, and stepby-step means controlled over the two sides of a metallic talking circuit in series for controlling the extent of operation of said movable element.

21. In a telephone system, a subscribers line, an automatic swltch including arms movable in twointersec'timg planes, means on said subscribers line for transmitting a varied number of -impulses to control said switch, means for moving said arms by a single-continuous motion in both directions, `and means controlled by said varying num.- ber of impulses for controlling the extent of motion of said arms.

22. In a telephone system, a subscribers line, an automatic switch including movable arms, means on said subscribers line for' transmitting a varied numberof impulses over the two sides of a metallic talking circuit in series'to control said switch, means for moving said arms by a single continuous motion in two directions, and means controlled by said varying number of impulses for controlling the extent of motion of said arms.

23. In atelephone s stem, an automatic switch including mova le arms, means for moving said arms by a single continuous motion in two intersecting planes, step-bystep means for controlling the extent of mo-v tion of said movable arms and circuits for controlling said operation.

24. In a telephone system, an automatic switch including movable arms, means for moving said arms by a single continuous motion in two intersecting planes and a stepbystep means controlled over a metallic circuit for controlling the extent of motion of said movable arms.

25. In a telephone system, an automatic switch including movable arms, means for moving said arms by a vertical motion, means for controlling the extent of said vertical motion, means for rotating said arms and means whereby vsaid vertical motion is translated without pause into said rotary motion, and circuits for controlling said operation. l

26. In a telephone system, an .automatic switch including an operating shaft, means for controlling the operation of said shaft in two directions through a single continuous motion and means forsimultaneously operating said controlling means at one speeg and said operating shaft at a second spee 27. lIna telephone system, an automatic switch including a movable element having motion 1n two intersecting planes, a single operating means for moving said element in both of said planes, means for causing the movement of said element in said two planes to be continuous and electrical circuits for controlling said operating means.

28. In a telephone system, an automatic switch including a movable velement having motion in two intersecting planes, asingle operating Ameans for moving said element in both of Vsaid planes, means for merging said two movements in different directions into a single movement, and means for controlling said operating means over a metallic circuit.

29. In a telephone system, lines divided into groups, an automatic switch including a movable element having motion in one Aco planeto select groups and motion in a plane at right angles thereto to find a line in the selected group, a single operating means 'for moving said element in both of said planes and means for causing the two movements tomerge into a single continuous movement.

In witness whereof, I hereunto subscribe my name this 19th da of July A. D. 1917.

Y f G RALD DE 2'@ 

